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How Forests Influence Local Rainfall
为什么森林能影响局地降水
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Trees release huge amounts of water vapor daily through transpiration—up to 1000 liters per large tree.
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This moisture rises, cools, and condenses into clouds, especially over dense tropical forests like the Amazon.
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Forest canopies also create rough surfaces that slow winds and encourage air to rise, enhancing cloud formation.
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Biogenic volatile organic compounds—released by leaves—form tiny particles that serve as cloud condensation nuclei.
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Deforestation reduces evapotranspiration and disrupts local circulation, sometimes cutting rainfall by 20–30% within decades.
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Satellite data shows ‘flying rivers’—atmospheric moisture streams—that originate in forests and supply rain far inland.
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Mountain forests are especially effective because terrain lifts moist air, triggering orographic precipitation.
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Urban planners now protect watersheds with native trees not just for soil, but to sustain reliable rainfall patterns.